Troubleshooting tips

Radio Control Boat Modeler, Feb 2003 by Turner, Jay

Much of the correspondence I receive deals with radio- and motor-related problems, but it's often difficult for me to solve a problem at a distance. There are, however, a number of particularly common radio problems, so I deal with some of them here. By following my tips, you should, I hope, be able to eliminate most of-if not all of!-these problems.

RANGE CHECK!

Before you put a new boat on the water, you should ask a friend to help you with a radio-range test. Have your friend take your boat at least as far away from you as you will ever run it-200 feet minimum. With the transmitter antenna fully extended, the rudder and speed control should operate smoothly and without hesitating.

If the boat passes this test, try it on the water; if it doesn't pass, you must correct the problem before you run the model. Common causes of radio-range problems

Check these in order:

1. Low battery voltage. This might be the most common cause of insufficient radio range. Make certain that the transmitter and receiver batteries are both fresh or fully charged. Do not trust the battery meter on your transmitter; such meters are notorious for giving incorrect readings.

2. Receiver antenna has been shortened or is coiled. Check the receiver antenna; never cut it, and never coil it inside the hull to make it fit "nicely." The antenna tube should be as close to the receiver as is practical. I run the full length of antenna wire out through the antenna tube so that part of it trails out at the end of the tube (this will not hinder radio reception). If your receiver antenna has been cut or is broken, contact its manufacturer to arrange a repair, or replace it.

We all know that radio equipment and water don't mix. A wet receiver may shut down completely, its range may be poor, or It may glitch. A wet servo will usually stop returning to Its neutral position and will instead move farther and farther toward one end of its travel.

If you get an RC car ESC wet, there's a good chance that it will be ruined; it certainly won't function until it has completely dried out. Strangely, however, the drive motor will operate just fine when it's wet; in fact, it will operate when it's completely immersed in water! Sometimes, when a boat sinks during a race because Its hatch came off or another boat punched a hole In its side, it will race to the surface and breach like a whale with the motor running at full throttle. This wears the motor brushes severely, but if you let it dry it out, the motor will usually run as well as it did when new.

No matter how tightly your boat's hatch is sealed, water will eventually find its way inside, and just one drop in the wrong place can cause radio problems. To avoid this, you need to waterproof your receiver and use a waterproof ESC. Many boaters encase their receivers in a balloon, but I find this awkward, and a balloon is easily punctured. Instead, I wrap the receiver and a piece of paper towel in plastic kitchen wrap; the paper will absorb any moisture that might get Inside. I use a small cable tie to secure the ends of the wrap around the wires. This isn't a completely waterproof setup (it will leak ltd; hull is ever completely filled with water!), but I haven't had a water-related radio problem since I adopted this technique.

GLITCH GREMLINS

ESC (electronic speed control) "glitching" is very common, and it means an interrupted throttle. Instead of reaching full speed, the motor stutters or cuts out entirely. Not only does this limit your top speed, but it is also hard on the motor, the ESC and the battery cells. This problem can sometimes be solved by following the steps previously mentioned; try them first.

If you still aren't successful, check the following.

1. Have you installed capacitors? Your ESC may require that you install one, two, or even three capacitors; always read your ESC's instructions, and don't run your boat without the required capacitors. Some ESCs require a Schottky diode to be installed across the power wires; because this diode is polarized, make sure that the end with the lighter color band is attached to the positive power wire.

2. Is the receiver or antenna too close to the power system? To reduce the chance of glitching, a receiver should be at least 3 inches away from the motor, ESC and power wires. Some hulls don't have enough room to allow this, but always strive to keep the receiver as far away from the power system as is practical. The same is true of the control wires that go from the receiver to the ESC; tape them out of the way of the power wires.

3. Too much power for your ESC? In very-high-power applications, ESCs with battery-eliminator circuitry (BEC) can have problems. One popular ESC is advertised to work with 6 cells, but when used for racing with low-turn motors, the cells' internal resistance causes their voltage to drop so low that the ESC turns itself off. As soon as this happens, the cell voltage rises and the ESC turns itself on again, and then the voltage drops. This all means severe glitching. The solution is either to use a separate receiver battery pack (recommended for racing) or a less powerful motor.